import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int initx=in.nextInt();
        int inity=in.nextInt();
        int x1=in.nextInt();
        int y1=in.nextInt();
        String ln="";//ver or hor
        if (x1==initx){
            ln="vert";
        } else if(y1==inity){
            ln="horiz";
        } else {
            System.out.println("NO");
        }
        boolean yes=true;
        for(int a0 = 0; a0 < n-2; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(ln.equals("horiz")){
                if(y!=inity){
                    yes=false;
                    System.out.println("NO");
                    break;
                }
            } else if(ln.equals("vert")){
                if(x!=initx){
                    System.out.println("NO");
                    yes=false;
                    break;
                }
            }
        }
        if(yes){
            System.out.println("YES");
        }
    }
}